A primary objective in bowling is that the bowler impart to the ball a combination of two rotary motions, called "roll" and "spin".
Most bowlers experience great difficulty in giving both these types of rotation to the ball simultaneously in any consistent manner.
Various solutions have been proposed for the problem described. Some devices have been designed which affect or control the position of the bowler's fingers. These include the devices of U.S. Pat. Nos. 3,038,723; 3,152,337; 3,224,012; 3,362,027; 3,563,545, and 3,595,575. These devices are not in common use and they are not effective to achieve the aims discussed.
Other devices have been proposed which control or limit the bending of the wrist. Examples are those disclosed in U.S. Pat. Nos. 1,469,315; 2,794,638; 2,924,458; 3,117,786; 3,235,258; 3,423,095; 3,512,776; 3,606,342; 3,704,994; 3,788,307; 3,829,090; 4,088,318 and 4,176,840. Such devices are sometimes partially effective in assisting with the so-called "lift" and resulting roll, but do not provide a consistent spin at the same time.
Other wrist supports have been designed which also control the middle fingers, but these, described in U.S. Pat. Nos. 3,467,379; 3,726,525; 3,770,270 and 3,880,426 are similarly ineffective.
Our experiments have revealed the presumed function of these and other devices as well as the reason why they fail to achieve the desired results. It is necessary to support and control both the wrist and the angle of the index finger, as will be seen below. Our invention, in providing both kinds of support, is effective in assisting the bowler to impart the desired combination of roll and spin to the ball in a consistent manner.